1. Field of the Invention
The present invention relates to an assembly station that loads heads onto the disk of a hard disk drive.
2. Description of Related Art
Hard disk drives contain magnetic disk which spin relative to one or more magnetic heads. The magnetic heads are suspended above the surface of the magnetic disk by an actuator arm which has a magnet/coil assembly that moves the heads relative to the disk. During operation, the head is separated from the surface of the disk by an air bearing that is created by the rotation of the disk.
Disk drives are typically assembled by first mounting a spin motor and actuator arm assembly to a baseplate, and then attaching the magnetic disk to the motor. To provide clearance for the installation of the motor and the magnetic disk, the disk and actuator arm are initially mounted so that the magnetic head is located away from the disk. After the magnetic disk and actuator arm are installed, the head is rotated to a position above the disk. The head loading process is typically performed with some type of automated tooling which lifts and rotates the magnetic heads.
Actuator arms typically have a large aspect ratio, resulting in an arm that is relatively flexible and weak. Consequently the arms tend to sag under the force of gravity. If multiple heads are being loaded onto the disk, the heads must be separated to assure clearance above the disk surface. Therefore most conventional head loading tools have means to separate and support multiple magnetic heads when the heads are being loaded onto the disk. One common type of head loading tool contains two sets of fingers which can engage the heads and move relative to each other in a scissor-like fashion. Relative movement of the fingers separates the magnetic heads, so that the heads clear the disk surface when the actuator arm is rotated above the disk. The separation of the magnetic heads must be sufficient to insure that the heads do not come into contact with the surface of the disk during the loading process. Contact between the head and the disk surface may cause damage to the head or disk, resulting in a defective drive unit. Defective drive units lower the yield of the assembly process and invariably raise the cost of production.
Relative movement between the actuator arms and loading tool may create particles that contaminate the drive. Most commercially available hard disk drive units contain rotary actuators that pivot about a bearing assembly. Therefore, to prevent the actuators arms from moving relative to the tool, the movement of the scissors must be primarily rotational when loading heads onto a disk. The prior art includes automated head loaders which rotate the disk drive while the heads are being loaded onto the disk. These devices are relatively expensive and are not conducive to use on a conveyor assembly system. It would therefore be desirable to have an inexpensive assembly station that can effectively load heads onto the disk of a hard disk drive.